1. Field of the Invention
The present invention relates to an illumination system, and more particularly, to an illumination system having a power line communication unit (PLC unit).
2. Description of Related Art
LEDs are semiconductor devices. The light emitting chips are mainly made of a compound semiconductor material containing III-V group chemical elements, for example, GaP, GaAs, and the like, and function on the principle of converting electric energy to light. That is to say, the compound semiconductor is powered to release excessive energy through the combination of electrons and holes, so as to emit photon (light). The LED can emit light without being heated or does not discharge to emit light. Therefore, the lifespan of the LED is up to 100,000 hours, and an idling time is not required. In addition, the LED has advantages of quick response speed (approximately 10−9 seconds), small volume, power-saving, low pollution, high reliability, and ease mass production. Thus, the LEDs have been intensively used in many fields, for example, light source and illumination device in large-scale bulletin boards, traffic lights, cellular phones, scanners, fax machines, etc.
Currently, the light emitting brightness and efficiency of the LEDs are continuously improved, and meanwhile the white LEDs with high brightness are successfully put into mass production, so the white LEDs have been gradually used in illumination devices such as indoor illumination and outdoor street lamp. However, as for the outdoor street lamps, the LED street lamps are generally designed to have a simple illumination function instead of bringing other added values to the passers-by or administrators.
Furthermore, illumination of a common-use street lamp is usually a high pressure sodium (HPS) lamp. A voltage needed for driving the street lamp usually ranges between 4000 volts and 5000 volts, and a stabilizer is required to be installed in the HPS lamp; therefore, a production cost and overall weight are increased virtually. In addition, because the street lamp is often installed in an outdoor environment, how to keep the street lamp clean has been one of the most important topics in illumination of the street lamp.